build: Fixed linking against libssh in thread library.

src/threads/CMakeLists.txt

@@ -7,7 +7,7 @@ set(LIBSSH_THREADS_PUBLIC_INCLUDE_DIRS
     CACHE INTERNAL "libssh public include directories"
 )
 
-set(LIBSSH_PRIVATE_INCLUDE_DIRS
+set(LIBSSH_THREADS_PRIVATE_INCLUDE_DIRS
     ${CMAKE_BINARY_DIR}
 )
 
@@ -24,7 +24,7 @@ if (WITH_STATIC_LIB)
 endif (WITH_STATIC_LIB)
 
 set(LIBSSH_THREADS_LINK_LIBRARIES
-    ${LIBSSH_LINK_LIBRARIES}
+    ${LIBSSH_SHARED_LIBRARY}
 )
 
 set(LIBSSH_THREADS_LINK_LIBRARIES